[Oracle] LeetCode 88 Merge Sorted Array 双指针

You are given two integer arrays nums1 and nums2, sorted in non-decreasing order, and two integers m and n, representing the number of elements in nums1 and nums2 respectively.

Merge nums1 and nums2 into a single array sorted in non-decreasing order.

The final sorted array should not be returned by the function, but instead be stored inside the array nums1. To accommodate this, nums1 has a length of m + n, where the first m elements denote the elements that should be merged, and the last n elements are set to 0 and should be ignored. nums2 has a length of n.

Solution

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class Solution {
public:
    void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {
        if(n==0)return;
        else if(m==0){
            for(int i=0;i<n;i++)nums1[i]=nums2[i];
            return;
        }
        else{
            vector<int> tmp;
            for(int i=0;i<m;i++)tmp.push_back(nums1[i]);
            int p1=0,p2=0;
            int cnt=0;
            while(p1<m && p2<n){
                if(tmp[p1]<nums2[p2]){
                    nums1[cnt]=tmp[p1];p1++;cnt++;
                }
                else{
                    nums1[cnt]=nums2[p2];p2++;cnt++;
                }
            }
            if(p2<n){
                for(int i=p2;i<n;i++){
                    nums1[cnt]=nums2[i];cnt++;
                }
                return;
            }
            else{
                for(int i=p1;i<m;i++){
                    nums1[cnt]=tmp[i];cnt++;
                }
                return;
            }
        }
    }
};